Interference No. 105,113
The specification explains:
A comparison between Figs. 4E and 4F [sic: 2E and 2F] reveals that an
increase in the grain size of the copper layer 440 has taken place. Traditionally,
the change in the grain size has been forced through an annealing process. In such
an annealing process, the wafer is subject to an elevated temperature that is
substantially above the ambient temperature conditions normally found in a clean
room. For example, such annealing usually takes place in a furnace having a
temperature generally around or slightly below 400 degrees Celsius, or about half
of the melting temperature of the electrodeposited copper. . . .
Absent such an annealing step, the traditional view is that the substantial
number of grains per given volume in such sub-micron structures significantly
decreases the electromigration resistance of the metal lines that are produced and
gives the material a higher resistivity. This is due to the fact that grain boundary
migration occurs with a much lower activation energy that trans-granular
migration. As such, conventional wisdom dictates that a separate annealing step
is required.
The present inventor has found that such a separate annealing step in
which the electrochemically deposited copper is subject to a subsequent high
temperature annealing process (e.g., at about 400 degrees Celsius) is not, in fact,
necessary. Rather, electrochemically deposited copper metallization having grain
sizes substantially smaller than the sub-micron structures that they fill may be
subject to an annealing process in which the annealing of the copper metallization
takes place at, for example, room temperature or at temperatures substantially
below 400 degrees Celsius where the annealing process is more easily controlled
and throughput is increased.
Id. at 11, l. 16 to p. 13, l. 3 (our emphasis). The reference to "furnace" in the first of these
paragraphs is clearly limited to prior-art, high-temperature annealing and thus does not
demonstrate an intent by the Ritzdorf inventors to employ an annealing furnace in their
invention, as asserted in Ritzdorf's opposition in arguing that this annealing furnace provides
written description support for the annealing "chamber" recited in Ritzdorf's claims.
Opposition 2, at 5, ¶ 8.
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